The field of the invention is that of intelligent portable objects such as a chip card or transponder, and more particularly data exchanges by inductive coupling within such an object.
It finds an application in particular in access control, identification or data processing (display, entry) by means of an intelligent portable object such as a chip card, an electronic label or the like.
Documents in the field of the invention will be cited.
The document EP0057602 describes an intelligent portable object for the payment of services. This device comprises an integrated circuit chip, integrated, via a bus grouping together conductive wires, with other components of the device, including an antenna, a display screen and an entry keyboard. This document therefore provides only the internal components communicating exclusively via a contactless connection with an external station.
The document U.S. Pat. No. 6,073,855B describes an apparatus for the reception, maintenance and transmission of information and data. The apparatus comprising a main computer and at least two cards to the PCMCIA format, placed in parallel in a dedicated compartment. An interface affords communication between the PCMCIA cards. The communication interface can divert the data, which must normally pass via a standard bus which physically connects the PCMCIA cards to the main computer, in order to accelerate the transmission of information and data, for example by capacitive, optical or inductive coupling. Since it is a case of accelerating the transfer rate, this document does not make provision for replacing the physical connection with a contactless link.
The document U.S. Pat. No. 5,537,126 describes a system for displaying information at a place of sale, by means of electronic display labels. The labels are in electromagnetic coupling with a conductor. A control circuit is used for producing an information signal which contains the address of the label and data. A modulator circuit converts an alternating current into an information signal and applies it to the conductor for transmission thereof to the display labels. Each of the labels is equipped with an electromagnetic coil coupled to the conductor. Each of the display labels is equipped with a manual initialisation switch. A microprocessor is also provided in the label as well as an internal memory.
The document DE4138131 describes a chip card with microprocessor, display screen and integrated memory supplied by a solar sensor. Communication between the card and an external unit in read/write mode is contactless, for example by optical, capacitive or inductive transmission. The microprocessor, the memory, the display and the solar energy sensor are physically connected to the inside of the card by conductors.
The document DE19604206 describes an intelligent portable object for the transmission of secure data. This intelligent portable object has a card body made from plastics material, to the format of a credit card. In part of the card a keypad is housed, with the function keys. Under the keypad galvanic conductors connect rows and columns together in a matrix to a control unit. The intelligent portable object is also equipped with an antenna, embedded in the body.
The document U.S. Pat. No. 4,874,934 describes a chip card which is composed of a central processing unit, data memories and memories for the programs, as well as a display control consisting of a chip. The card components are connected physically.
Contactless intelligent portable objects comprising a contactless communication interface able to send or receive data by inductive coupling with a station are therefore known. Generally, the contactless communication interface comprises an antenna coil connected to a capacitor, an integrated circuit such as a chip or another component. Contactless intelligent portable objects have a peripheral circuit such as a display and a chip connected to this peripheral circuit. The chip performs identification and/or authentication functionalities, referred to as “central” or “principal” with respect to the so-called “peripheral” display function of the display.
These peripherals, for example the displays, have the drawback of having characteristics in terms of operating voltage and current which are not easy to make compatible with those of the chips. In addition, implementing connections between the chip and the peripheral is detrimental to the production cost of the intelligent portable objects.
The invention aims to remedy these drawbacks, and is defined in the claims.